Boon-Seang Chu

Performance of a lipase-catalyzed transesterified palm kernel olein and palm stearin blend in frying banana chips

Abstract The frying performance of an enzymatically transesterified palm stearin and palm kernel olein (1:1 by weight) blend was compared with its control (physical mixture or no enzyme added) and a commercial plastic frying shortening (CS). The samples were used as deep-fat frying media at 180°C for banana chips for seven consecutive days. The samples were then analysed for iodine value (IV), free fatty acid (FFA) content, peroxide value (PV), thiobarbituric acid (TBA) value, p-anisidine value (AV), total polar compounds (TPC), fatty acid composition, specific extinction, E1%1cm at 233 and 269 nm, polymer contents, viscosity and colour indices. The fried banana chips were analysed for acceptability by sensory evaluations. Storage properties of the banana chips were also evaluated by trained sensory panellists and a modified TBA test. The transesterified blend was found to have significantly (P 0.05; for all the attributes tested) between the acceptability of the banana chips fried by the transesterified and control blends. However, the banana chips fried in CS had significantly (P

Enrichment and quantification of monoacylglycerols and free fatty acids by solid phase extraction and liquid chromatography-mass spectrometry

Quantification of monoacylglycerols (MAG) and free fatty acids (FA) is of interest in biological systems, in food, cosmetic and pharmaceutical products. This manuscript describes and validates a reversed phase liquid chromatography-tandem mass spectrometry based approach for simultaneous quantification of these analytes in fats and oils. Purification and concentration of MAG/FA were performed using cation exchange solid phase extraction, which allowed elimination of the abundant triacylglycerols. Following cleanup and concentration, the analytes were separated and detected with the aid of volatile ammonium-formate buffer. MAG were detected in positive ion mode, while FA were detected in negative ion mode. The method was validated by the method of standard additions and using stable isotope labeled internal standards. The results confirm the feasibility of quantifying these two classes of analytes simultaneously without any chemical derivatization. The obtained main quantitative features include: (1) lower limits of quantification 1-30ppm for MAG analytes, (2) lower limits of quantification 90-300ppm for FA analytes, (3) averaged inter-batch precision 6%, and (4) averaged bias -0.2% for MAG and 0.5% for FA. Various animal fat and vegetable oil samples were characterized for their MAG/FA profile indicating the usefulness of the method to address quality and authenticity of fats and oils.

The bioaccessibility of eicosapentaenoic acid was higher from phospholipid food products than from mono- and triacylglycerol food products in a dynamic gastrointestinal model

The bioaccessibility of eicosapentaenoic acid (EPA) in the forms of monoacylglycerol (EPA-MAG), triacylglycerol (EPA-TAG), and phospholipid (EPA-PL) during gastrointestinal passage was compared in this study using a dynamic gastrointestinal model (TIM system). The TIM system simulated the average upper gastrointestinal tract conditions of healthy human adults after intake of a meal (fed state conditions). In this study, the three EPA-rich oils were separately homogenized with full fat milk to obtain oil-in-water emulsions. Plain yogurt was added into the mixture at an emulsion/yogurt ratio of 4:1 (w/w) as the food matrix of the test products. The results show that the test meals containing EPA-PL left the stomach compartment most efficiently in comparison with the gastric emptying of EPA-MAG and EPA-TAG. The PLs also showed a significantly (P < 0.05) higher bioaccessibility of EPA (75–80%) in comparison with MAG (30%) and TAG (38%). The better gastric emptying of EPA-PL was likely related to the more stable emulsion of EPA-PL in the test meal. EPA-PL was delivered within the meal matrix into the duodenum instead of floating on the top of the test meal matrix. EPA-MAG had the highest amount of EPA that did not leave the stomach (68% of the test meal). The results from this work indicate that EPA-PL is a more effective form of EPA for a higher lipid bioaccessibility than MAG and TAG under the test conditions.

Evaluation of the efficacy of orange roughy (Hoplostetbus atlanticus) oil in subjects with dry skin

Moisturizers have beneficial effects in treating dry skin. The objective of this study was to evaluate the effect of orange roughy (Hoplostethus atlanticus) oil, a marine‐derived wax ester, on skin dryness in comparison with a reference commercially available petrolatum‐based moisturizer (Vaseline) and untreated control. Subjects (n = 24) with moderate to severe skin dryness at the lower limb of legs (Study 1) and with certain degree of skin dryness on the face and the forearms (n = 22, Study 2) were treated twice a day for 42 consecutive days with the test products in randomized clinical trials. Transepidermal water loss (TEWL) was measured at the beginning and the end of Study 1, whereas skin hydration was measured at the beginning, after 3 and 6 weeks of the application (the end of the study) in Study 2. Changes in the skin dryness were assessed by a dermatologist using a video microscopy. In Study 1, the dryness score of skin applied with orange roughy oil improved significantly (P < 0.01) in 6 weeks. The skin looked smooth with no or little dry scaly skin. Orange roughy oil was evaluated with a 60% efficacy in treating skin dryness by the expert, which comparable to that of petrolatum (68%). No significant change in TEWL was found either in orange roughy oil or petrolatum treatment, although the values showed a tendency to improve in both cases. Similarly, the results of the skin capacitance in Study 2 showed a significant improvement of the skin symptoms after 3 and 6 weeks. These results showed that the performance of orange roughy oil in treating skin dryness was comparable to that of petrolatum.

Determination of iodine value of palm olein mixtures using differential scanning calorimetry

Differential scanning calorimetry (DSC) was used to determine the iodine value (IV) of various palm olein (PoO) mixtures. Eight different PoO mixtures, namely, PoO:PKO, PoO:CoO, PoO:PS, PoO:PO, PoO:CaO, PoO:OeO, PoO:CnO and PoO:SFO were prepared at different ratios (w/w) to give various IV (PKO represents palm kernel olein; CoO, coconut oil; PS, palm stearin; PO, palm oil; CaO, canola oil; OeO, olive oil; CnO, corn oil; and SFO, sunflower oil). Each sample was then scanned from 80 to - 100 °C at -5 °C/min using a DSC. All the mixtures showed two exothermic peaks in their cooling thermograms, except PoO:SFO mixtures which showed three peaks. Results of stepwise multiple linear regression (SMLR) analysis showed that five independent variables extracted from each of these peaks, namely, on-set temperature, off-set temperature, peak temperature, peak height and peak enthalpy could predict well the IV of each mixture. The calibration models developed showed appreciable effectiveness, re-producibility and accuracy, and specificity towards the calibration data set. A shared calibration model for each group of PoO mixtures i.e. high-lauric (PoO:PKO and PoO:CoO), high-palmitic (PoO:PS and PoO:PO) and high-oleic (PoO:CaO and PoO:OeO) mixtures was also developed. SMLR analysis showed that the shared models were also capable in predicting IV of the PoO mixtures, even though the coefficient of determination, R2, was slightly lower than that of their individual models. The shared calibration models also had good reproducibility and accuracy when compared with the standard chemical method. In conclusion, DSC provides an effective method in determining IV for routine analysis in the industries, whereby one single model could be calibrated for the use of all oil and fat products that have similar chemical compositions such as high-lauric, high-palmitic or high-oleic mixtures in the industry.

Selective adsorption of vitamin E from palm fatty acid distillate on silica-packed fixed-bed columns

Understanding the behavior of vitamin E adsorption during chromatographic separation was useful for a better control of the process. In this study, a pre-concentrated vitamin E fraction from palm fatty acid distillate (PFAD) was subjected to a normal phase silica-packed fixed-bed column for further purification. The effect of various operational parameters i.e. column bed height, vitamin E inlet concentration, column temperature and flow rate on column performance were detailed. It appeared that the breakthrough curves of all systems showed a typical S-shaped profile. The service time of the column increased when increasing the column bed height, or reducing the inlet concentration, column temperature and flow rate. It was found that column efficiency in terms of adsorbent usage rate could be improved by decreasing the inlet concentration and flow rate. Decreasing the column temperature resulted in higher column capacity, suggesting that the adsorption of vitamin E on silica was an exothermic process. The Bed Depth Service Time (BDST) model described the adsorption process well, with coefficient of determination ranging from 0.92 to 0.99 and low residual sum of square (< 0.28) and standard error (< 0.35). The model could explain the characteristic operational parameters well except for the effect of flow rate in this study.

Time-resolved fluorescence observation of di-tyrosine formation in horseradish peroxidase upon ultrasound treatment leading to enzyme inactivation

The application of ultrasound to a solution can induce cavitional phenomena and generate high localised temperatures and pressures. These are dependent of the frequency used and have enabled ultrasound application in areas such as synthetic, green and food chemistry. High frequency (100kHz to 1MHz) in particular is promising in food chemistry as a means to inactivate enzymes, replacing the need to use periods of high temperature. A plant enzyme, horseradish peroxidase, was studied using time-resolved fluorescence techniques as a means to assess the effect of high frequency (378kHz and 583kHz) ultrasound treatment at equivalent acoustic powers. This uncovered the fluorescence emission from a newly formed species, attributed to the formation of di-tyrosine within the horseradish peroxidase structure caused by auto-oxidation, and linked to enzyme inactivation.

Effect of sucrose on thermal and pH stability of Clitoria ternatea extract

The aim of this work was to investigate the effect of sucrose on the stability of Clitoria ternate extract against thermal and pH degradations. Lyophilised extract of the flower (1 mg/ml) was added into a series of sucrose solutions with concentrations ranging from 0.1% to 20% at pH7. The thermal stability of the extract in the solutions at 60C was monitored using a UV-VIS spectrophotometer over 24 days. High temperature (60C) accelerated degradation of the anthocyanin-rich extract but the presence of sucrose appeared to have slowed down the degradation process. However, sucrose asserted no protective effect against pH even at a concentration of 20%. It was thought that sucrose enhanced the thermal stability of anthocyanins by reducing water activity, partially preventing nucleophilic attack at the pyrylium ring of anthocyanins by water molecules. The present work provides some useful information for evaluating the potential of C. ternatea extract on food applications.

Desorption of vitamin E from silica-packed fixed-bed column by isopropanol.

Desorption of vitamin E from silica-packed fixed-bed column was studied as functions of column bed height, column temperature and flow rate of isopropanol. Isopropanol was the desorbing solvent and it was eluted through the columns saturated with vitamin E. The desorption profiles of all systems showed that vitamin E might desorb at two distinct rates simultaneously. The slow desorbing step was the rate-controlling process for recovery of vitamin E. The desorption rate increased with the decrease of column bed height and flow rate, but increased with increasing column temperature. This indicated that the desorption process was an endothermic process. The percentage recovery of vitamin E upon completion of desorption was considered high for all systems, ranging from 94.8 to 98.8%, with vitamin E concentration in the extract of 18.5-21.5%. Although the bed height, column temperature and flow rate were functions of desorption rate, it appeared that percentage recovery and vitamin E concentration in the extract were rather unaffected by the operating conditions tested if the column was eluted by isopropanol for a sufficient time to desorb vitamin E. Nevertheless, the use of isopropanol would be more efficient if desorption was carried out at lower flow rate and higher column temperature.